Nathan Mehl posted,
| Thank heavens for VERPs, or I might never have figured out where
| this bounce message had come from. Note the STUNNINGLY useful
| "Press F1 for help with VNM error codes." I'm also impressed
| by the "Abco de Buck@[EMAIL PROTECTED]" destination address.
The NDN Nathan shared has to take a back seat to those from Prodigy. Prodigy
sends back simply the unreachable user ID with no information about the re-
jected message from you: no Received: headers for its travel to Prodigy, no
Subject: to help you identify it, nothing. I was getting bounces for a Prod-
igy address that was not on the list; a subscriber was forwarding the list to
Prodigy but not changing the envelope sender to her forwarding point, and
Prodigy was doing one thing right by sending the NDN to the envelope sender
(a VERP would have worked beautifully if I had such a facility available),
but with no Received: headers I couldn't narrow down the routing [much less
find out specifically who was forwarding it].
Lacking VERPs, my usual method of tracking down a bounce when I cannot tell
the exact address is to send each suspect a probe letter with his/her address
in the subject. Generally the returned Received: headers narrow the suspects
down to a handful of subscribers, but Prodigy didn't return the Received:
headers. Because of features of my own list I could rule out about 15% of
the subscribers, but most were still possible perps. And identification by
returned Subject: line wouldn't work anyway, because Prodigy didn't return
the subject line! Their system assumes that there is no such thing as for-
warding and that, if they tell you such a Prodigy ID is invalid or that its
mailbox is full, you can simply stop writing to that Prodigy user.
| Anybody out there have any idea what nightmarish cruft generated
| this one?
| To: Smtp@Mail@Alg[<[EMAIL PROTECTED]>]
| Smtp@Mail@Alg["Lone Deranger" <[EMAIL PROTECTED]>]
| Cc: Smtp@Mail@Alg[<[EMAIL PROTECTED]>]
| Subject: Re: [anacam] replying
It sent you back the subject, Nathan, so that puts it light years ahead of
Prodigy. If Prodigy had sent the subject back, I could have sent one probe
letter to each of the 80% of my subscribers who might have been doing the
dirty deed. What I had to do instead ... gad.
Long story, but my list had eight aliases, of which two I do not publicize
[well, I don't publicize three, but one of them is simply of little use and
not of any sensitivity]. The other six plus my logname made for seven possi-
ble envelope senders.
I was getting these bounces only when digests went out, not for each reflec-
tor item. The list has one sublist, and the sublist was busy at that time,
but still the number and frequency of mystery NDNs from Prodigy matched those
of digest issues without any esxtra ones for sublist articles. So the mis-
creant had to be a digest-mode subscriber who was not on the sublist. [Well,
maybe not; perhaps she was forwarding digests and receiving but not forward-
ing sublist articles. OK, so it was a hunch to eliminate sublist members.]
There were 1220 digest-mode subscribers not receiving the sublist. I had
seven envelope sender addresses available, so I divided them into seven
groups of 174 or 175 and sent out a probe letter explaining the situation
briefly: that there was a mystery bounce; that the system bouncing the
messages was not obeying the rules and not supplying sufficient information
for me to pinpoint the bad address; the only way I could track it down was to
send out four rounds of these probe letters; that 6/7 of them would be elimi-
nated on the first round and not have to get any more of these; but that 1/7
would receive the second probe, and so on; that no response was necessary;
and that I apologized for the situation and thanked them for their forebear-
ance. About three or four of them did answer, assuring me they'd gotten the
probe or that they swore they weren't the ones forwarding the list, or asking
if they might have done something wrong. None complained or objected.
About twenty minutes later Prodigy bounced one back, and the Apparently-To:
address of the NDN identified which group included the malefactor. I divided
the 175 recipients who had had that envelope sender on their copies of the
first probe into seven groups of twenty-five and sent out probe letter #2,
where I assured them that it was just the luck of the draw that they were
still in for the second round and not an indication that I suspected them any
more than the 1045 subscribers who had been eliminated.
Then the bounce for probe #2 came and it eliminated 150 more subscribers. I
divided the remaining twenty-five into seven groups of three or four, and
probe #3 eliminated twenty-two more people. For probe #4 I wrote the most
apologetic letter yet, and sent each a copy with a different envelope sender
(finally getting the functionality of VERPs). When the bounce came about ten
minutes later, I canned the culprit.
At least Nathan's subscriber's site returned the Subject: line. If Prodigy
had done that, I could have sent each of the 1220 a personally tailored sub-
ject (Subject: test to [EMAIL PROTECTED]) -- that would have meant one con-
nection per user, but so do VERPs -- and seen in one pass who was causing the
trouble.
